Due date help

Hi! Got my BFP on clearblue digital this morning at 16 DPO. Have a question about due date because I ovulated on Oct. 10 but the first day of my last period was Oct. 1. Since I have very short periods of 24 days this adds up perfectly... (Today is Oct 26 and I'm 16 dpo). But my due dates vary depending on what date I enter. If I go off of Oct 1 then I'm due July 8. But if I got off the date I conceived, Oct 10, I'm due July 3. Seems like a big difference! Any thoughts?